Added HTK format support to sox_io's save & info (#1308)

* Cherry pick 3488f31 from #1276 
* Cherry pick d2861fc from #1291

Author: imaginary-person

test/torchaudio_unittest/backend/sox_io/info_test.py

@@ -205,7 +205,7 @@ def test_ulaw(self):
         assert info.encoding == "ULAW"
 
     def test_alaw(self):
-        """`sox_io_backend.info` can check ulaw file correctly"""
+        """`sox_io_backend.info` can check alaw file correctly"""
         duration = 1
         num_channels = 1
         sample_rate = 8000
@@ -221,6 +221,22 @@ def test_alaw(self):
         assert info.bits_per_sample == 8
         assert info.encoding == "ALAW"
 
+    def test_htk(self):
+        """`sox_io_backend.info` can check HTK file correctly"""
+        duration = 1
+        num_channels = 1
+        sample_rate = 8000
+        path = self.get_temp_path('data.htk')
+        sox_utils.gen_audio_file(
+            path, sample_rate=sample_rate, num_channels=num_channels,
+            bit_depth=16, duration=duration)
+        info = sox_io_backend.info(path)
+        assert info.sample_rate == sample_rate
+        assert info.num_frames == sample_rate * duration
+        assert info.num_channels == num_channels
+        assert info.bits_per_sample == 16
+        assert info.encoding == "PCM_S"
+
     def test_gsm(self):
         """`sox_io_backend.info` can check gsm file correctly"""
         duration = 1

test/torchaudio_unittest/backend/sox_io/save_test.py

@@ -317,6 +317,12 @@ def test_save_gsm(self, test_mode):
         self.assert_save_consistency(
             "gsm", test_mode=test_mode)
 
+    @nested_params(
+        ["path", "fileobj", "bytesio"],
+    )
+    def test_save_htk(self, test_mode):
+        self.assert_save_consistency("htk", test_mode=test_mode, num_channels=1)
+
     @parameterized.expand([
         ("wav", "PCM_S", 16),
         ("mp3", ),

torchaudio/backend/sox_io_backend.py

@@ -195,7 +195,7 @@ def save(
             When ``filepath`` argument is file-like object, this argument is required.
 
             Valid values are ``"wav"``, ``"mp3"``, ``"ogg"``, ``"vorbis"``, ``"amr-nb"``,
-            ``"amb"``, ``"flac"``, ``"sph"`` and ``"gsm"``.
+            ``"amb"``, ``"flac"``, ``"sph"``, ``"gsm"``, and ``"htk"``.
         encoding (str, optional): Changes the encoding for the supported formats.
             This argument is effective only for supported formats, such as ``"wav"``, ``""amb"``
             and ``"sph"``. Valid values are;
@@ -294,6 +294,9 @@ def save(
     ``"gsm"``
         Lossy Speech Compression, CPU intensive.
 
+    ``"htk"``
+        Uses its default single-channel 16-bit PCM format.
+
     Note:
         To save into formats that ``libsox`` does not handle natively, (such as ``"mp3"``,
         ``"flac"``, ``"ogg"`` and ``"vorbis"``), your installation of ``torchaudio`` has

torchaudio/csrc/sox/io.cpp

@@ -97,6 +97,10 @@ void save_audio_file(
     const auto num_channels = tensor.size(channels_first ? 0 : 1);
     TORCH_CHECK(
         num_channels == 1, "amr-nb format only supports single channel audio.");
+  } else if (filetype == "htk") {
+    const auto num_channels = tensor.size(channels_first ? 0 : 1);
+    TORCH_CHECK(
+        num_channels == 1, "htk format only supports single channel audio.");
   }
   const auto signal_info =
       get_signalinfo(&tensor, sample_rate, filetype, channels_first);
@@ -233,6 +237,12 @@ void save_audio_fileobj(
       throw std::runtime_error(
           "amr-nb format only supports single channel audio.");
     }
+  } else if (filetype == "htk") {
+    const auto num_channels = tensor.size(channels_first ? 0 : 1);
+    if (num_channels != 1) {
+      throw std::runtime_error(
+          "htk format only supports single channel audio.");
+    }
   }
   const auto signal_info =
       get_signalinfo(&tensor, sample_rate, filetype, channels_first);

torchaudio/csrc/sox/types.cpp

@@ -20,6 +20,8 @@ Format get_format_from_string(const std::string& format) {
     return Format::AMB;
   if (format == "sph")
     return Format::SPHERE;
+  if (format == "htk")
+    return Format::HTK;
   if (format == "gsm")
     return Format::GSM;
   std::ostringstream stream;

torchaudio/csrc/sox/types.h

@@ -17,6 +17,7 @@ enum class Format {
   AMB,
   SPHERE,
   GSM,
+  HTK,
 };
 
 Format get_format_from_string(const std::string& format);

torchaudio/csrc/sox/utils.cpp

@@ -314,6 +314,13 @@ std::tuple<sox_encoding_t, unsigned> get_save_encoding(
         throw std::runtime_error(
             "mp3 does not support `bits_per_sample` option.");
       return std::make_tuple<>(SOX_ENCODING_MP3, 16);
+    case Format::HTK:
+      if (enc != Encoding::NOT_PROVIDED)
+        throw std::runtime_error("htk does not support `encoding` option.");
+      if (bps != BitDepth::NOT_PROVIDED)
+        throw std::runtime_error(
+            "htk does not support `bits_per_sample` option.");
+      return std::make_tuple<>(SOX_ENCODING_SIGN2, 16);
     case Format::VORBIS:
       if (enc != Encoding::NOT_PROVIDED)
         throw std::runtime_error("vorbis does not support `encoding` option.");
@@ -417,8 +424,12 @@ unsigned get_precision(const std::string filetype, caffe2::TypeMeta dtype) {
   if (filetype == "amr-nb") {
     return 16;
   }
-  if (filetype == "gsm")
+  if (filetype == "gsm") {
     return 16;
+  }
+  if (filetype == "htk") {
+    return 16;
+  }
   throw std::runtime_error("Unsupported file type: " + filetype);
 }